Printing machines of the type to which the present invention relates are known, for example see German Patent No. 407369. The machine there described permits essentially continuous printing on a substrate or web of paper or the like. To print with a single color, two partial printing stations are provided which cooperate with a common impression or printing cylinder. The partial printing stations each have a plate cylinder, with a respectively associated inker. For offset printing, each plate cylinder has an associated blanket cylinder and a damper. The plate on the plate cylinder extends over half the circumference of the plate cylinder, and the plates are so arranged that the beginning of the printing line on the substrate of one plate cylinder precisely matches the end of the printed image of the other plate cylinder. Thus, by passing a substrate web under the plate cylinders, the substrate web can be printing continuously without intervening margins.
The printing machine requires, for printing of one color, two plate cylinders and two inkers. If this machine is to be operated under ordinary customary printing conditions, for example to print a book, advertising material, or the like, that is, printed material which has margins, the same color ink must be used with the partial printing station. The interruption of printing by the attachment grooves of the plates is not bothersome when printing books, advertising material, or other material intended for reading, pictorial representation or manual handling since the margin is usually provided anyway. The image to be printed with one color, in the machine, then is copied on two plates, one on each of the partial printing stations, which then must be accurately and precisely positioned relative to each other to maintain proper alignment and register.